Apple has released an update for late 2012 iMac models that fixes issues related to sleep and Thunderbolt, as well as compatibility when using 5GHz Wi-Fi frequencies. The update is recommended for all "late 2012" iMacs.

This update is recommended for all iMac (late 2012) models. This update contains general performance fixes pertaining to sleep and Thunderbolt, and improves compatibility when using the 5GHz band in Wi-Fi.

Boot ROM or SMC Version Information: After Update is complete:

Build version: 010A.05
ROM version: IM131.88Z.010A.B05.1211151146

It's not clear if this is in addition to the Wi-Fi Update released earlier today, or if it includes that fix as well as a few more iMac-specific ones.

I wonder if this fixes the unmount on sleep w/ USB 3 hard drives. Otherwise what other sleep issues is the new iMac having? (Not home to try right now). Curious b/c the USB 3 issue was the only one I experienced. I wish Apple was more detailed in their update synopsis.

__________________Walled Garden ≠ Prison:"People who use Apple products considered their options, and chose Apple. If they regret their decision, they can dump it at any time."-- Harry McCracken, Technologizer.com

I posted this in another thread last night - I spent some time on the phone last night with Apple support after both of yesterday's updates failed on my 27", 2012 iMac. They were surprised at the updates not working for me and confirming that, yes, as best they could tell the updates should work on both the 21" and 27" iMacs. They downloaded info from my machine to forward on to engineering and we're scheduled to talk again on Wednesday to see what they've found out about this problem. I told them that there were others besides me experiencing this issue.

Any rhyme or reason we can figure out here? Anyone with a 27 incher that had either or both of today's updates work? I'm seeing posts where the updates worked on 21" machines, and failures on 27" machines.